4ku/5k head (Twin row timing chain not lining up)

[Thomasdillon]

Hi all, 

recently purchased a twin row timing chain kit. Went to install it lastnight and things are off by a couple mm. 
 

cam and crank didnt move at all during disassembly. Put the factory single row back on to be sure and it lined up perfect. 
 

i could get the crank pulley on and the cam locator dowel on but the cam pulley bolt hole was off by about 2/3mm. 
 

i ended up getting it on by reversing the crank by about a mill or so. 
 

basically, will this damage the motor. It was the slightest movement to get it on but now I'm worried ahah. 
 

spoke to the supplier (oldscoolautos) and theyve told me to redrill the locator pin hole on the cam pulley. 
 

just after some opinions on this. 
 

cheers 

[Thomasdillon]

Note: motor also turns freely with no resistance 

[altezzaclub]

So, you have effectively turned the cam timing forward, when you turned the crank backwards. If you're keen you could work out how many degrees you have moved it by holding a protractor in front of it. This means the cam will open valves earlier and close them earlier, and the crucial one for power is closing the inlet valve as the piston comes up. With the protractor you could measure when the inlet valve opens and closes, the stock cam has a duration of 246deg on both inlet and exhaust, and they are symmetrical around TDC on the exhaust stroke. I haven't got stock cam figures, but this sort of thing-

" Inlet opens 28BTDC closes 56ABDC, exhaust opens 56BBDC closes 28ATDC" for a hot Kelford cam.

Closing the inlet later moves the power up the rev range, so you can look forward to more power up top and less down low, although I'm quite certain you won't notice the difference, especially if the cam is stock. Also with that, you needn't worry about damage to the valve/pistons with a few degrees on a stock motor. If the head had been skimmed for compression and a wild cam with giant overlap fitted, cam timing gets more important.

Any wear in the chain, and fitting the tensioner, will pull the cam backwards and lessen the effect of the advance.

You could carefully measure the cam wheel in relation to the teeth and drill a couple more holes in it, Datsun 1600s had a couple of holes 4deg apart relative to the locating pin, and we used to drill another so we had 4,8,12deg adjustment, and each chain tooth was 16deg.

"Note: motor also turns freely with no resistance ' That is important and very good news for you..

[Banjo]

Hi Thomas,

                   There are a number of threads on this site, about installing the timing chain, & associated pullies on the K Series engine.  Here a link, to one I did about 10 years ago.

https://www.rollaclub.com/board/topic/71502-fitting-k-series-camshaft-timing-chain/#comment-696083

Frankly, the very small amount the hole position in the camshaft sprocket is out, is not going to create any issues at all; & You will not notice, any difference, in performance, unless the engine was highly modified, which it appears, not to be. 

Good question, but just put it back together as is, & You won't have any issue, or worries at all.

Cheers Banjo

[Thomasdillon]

You’ve allowed me the pleasure of sleeping tonight hahaha. Thank you fellas 

 

much appreciated 

[Banjo]

Our Pleasure !  Just make sure everything lines up, as per my pic below.

The keyway on the crankshaft sprocket, must be facing perfectly vertical (in line with the bores of the cylinders; when You fit the chain.  I noticed in your photo, it was at about 11:00 o'clock.  This is particularly important, when carrying out a timing chain changeover, with the engine in the car, as they normally are tilted slightly, to wards the manifolds, side of the engine.

Good Luck, & let us know how You go.

Cheers Bango

 

 

[Thomasdillon]

As per my photos you’re right, it seems that I was a little “pre TDC” when I did the chain swap. 

This arvo and did a few full rotations until I got the timing marks all lined up as per your photos, whacked the crank pulley on and had the timing mark line up up with the 0 of the timing cover. 
 

I think we’re good, I hope at least! 
 

theoretically, if nothing moved during the swap apart from me winding crank back a very little to account for old chain stretch we should be in the exact same position pre removing the chain. 

she was a humdinga runner when she came in the shed, let’s hope it’s the same on the way out haha.